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composite wet layup with micro ballon mixed Epoxy

Old 07-17-2008, 03:58 PM
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Default composite wet layup with micro ballon mixed Epoxy

Hi fellows.

A friend of mine has suggested on reducing weight of a structure by mixing 30 % microballon in the epoxy....and duing the wet layup with this mix.

It is known to me that the microballon is a finishing additive and not a structural one thus weakening the entire structure....besides, when baging the mold in vacum the microballon will end up "floating" on the surface because you can't force the microballon into the cloth (carbon in this case) the other thing that comes to my mind is that the cloth will absorb the epoxy and leave the microballon dry...

The last thing that i think of is that it will not reduce the weight as the entire mix will be more "dry" and it will require a larger amount of gule to saturate the cloth.

your inputs are apreciated!
Old 07-18-2008, 11:51 AM
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Default RE: composite wet layup with micro ballon mixed Epoxy

I've been experimenting with light weight in composites; carbon and epoxy laminations. I've got a 30' carbon fiber mast on my people-sized boat that got me thinking about some new (to me anyway) methods. My mast is all carbon but is not coated on the exterior but the carbon is just wet enough to be hard but is SO dry looking I was baffled at how they achieved it...the 30' mast is on a high tech 18' A-cat catamaran and weighs only 16lbs.

I've tested this with interesting results. When vacuum bagging, I wet out the first layer of lightweight cloth in an attempt to eliminate pin holes as much as possible. I usually use a 2.5oz or less cloth (satin weave is really nice for this). Before laying it in the mold, I wet out the glass and squeegie the excess resin from it with moderate pressure (you still need enough to maintain a bond to the outer finish in the mold and/or eliminate as many pin holes as possible). For the subsequent layer of carbon, with it on a flat surface, I squeegie in the resin until it is fully wetted, then I start blotting with paper towels. There's enough resin between the fibers that when compressed under vacuum, they bond very well, but it doesn't leave enough resin to fill the voids in the weave. The carbon comes out looking almost dry and very very light. I'll be laying up a full part next week with this method. I built a full part two weeks ago without blotting and with a fully wetted out fabric (a 36" X 8" part that forms 1/2 of a boat hull). I achieved 5.2oz with the cured lamination. I'm excited to see what blotting the carbon will achieve. I might be able to do away with the added steps of the bleeder ply and breather material in the vacuum bag if I can get this right.

Old 07-18-2008, 01:19 PM
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Default RE: composite wet layup with micro ballon mixed Epoxy

Hello Jake.

What we do in the industry is ..after the cloth is in the mold we lay a layer of peel ply and a certain nylon with many many tiny holes in it every 1/2 an inch and a layer kind of cotton fabric which sucks the left resin in to it and then place it into the vacum bag...

The resault is that not only the amount of resin is soaked in the cotton fabric but by peeling of the peel ply we actually get a very dry looking surface.
Old 07-21-2008, 12:49 PM
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Default RE: composite wet layup with micro ballon mixed Epoxy

I do the same thing now with a bleeder ply and felt layer. Although I've used peel-ply in the past, with the very thin laminations I'm making, the parts will not hold up to the efforts required to remove the peel ply. I'm laying up parts composed of 1 layer of 5.7oz carbon fabric and an outer layer 2oz fiberglass. I suppose if I cut the peel ply in narrow strips I could remove it but I can't imagine the part would withstand removal of large pieces of peel-ply without buckling.

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